A method includes providing a shape memory polymer in a permanent shape, where the permanent shape is at least part of a predetermined part shape, converting the shape memory polymer from the permanent shape into a temporary shape, where the temporary shape is more open than the permanent shape. The method further includes spraying a material onto at least one surface of the shape memory polymer in its temporary shape and reverting the shape memory polymer, having the material on the at least one surface, back to the permanent shape.
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1. A method of using shape memory polymers, the method comprising: providing a shape memory polymer in a permanent shape, the permanent shape being at least part of a predetermined part shape; converting the shape memory polymer from the permanent shape into a temporary shape, the temporary shape being more open than the permanent shape; spraying a material onto at least one surface of the shape memory polymer in its temporary shape; reverting the shape memory polymer, having a material on at least one surface, back to the permanent shape; and after reverting the shape memory polymer to its permanent shape, then curing the material by applying heat thereto.
11. A method of using shape memory polymers, the method comprising:
providing a shape memory polymer in a permanent shape, the permanent shape being at least part of a predetermined part shape, wherein the shape memory polymer is a preform screen, and wherein the permanent shape of the shape memory polymer is at least a surface of the predetermined part shape;
converting the shape memory polymer from the permanent shape into a temporary shape, the temporary shape being more open than the permanent shape;
spraying a material onto at least one surface of the shape memory polymer in its temporary shape;
reverting the shape memory polymer, having the material on the at least one surface, back to the permanent shape;
after the reverting, curing the material, thereby forming a preform having the predetermined part shape; and
removing the preform from the shape memory polymer preform screen.
7. A method of using shape memory polymers, the method comprising: providing a shape memory polymer in a permanent shape, the permanent shape being at least part of a predetermined part shape; converting the shape memory polymer from the permanent shape into a temporary shape, the temporary shape being more open than the permanent shape; spraying a material onto at least one surface of the shape memory polymer in its temporary shape; reverting the shape memory polymer, having a material on at least one surface, back to the permanent shape, the reverting being accomplished by: heating the shape memory polymer to a temperature above its switching temperature; cooling the shape memory polymer to a temperature below its switching temperature to substantially fix the shape memory polymer in the permanent shape; and after reverting the shape memory polymer to its permanent shape, then curing the material when the shape memory polymer is heated.
2. The method as defined in
heating the shape memory polymer to a temperature above its switching temperature; and
applying a mechanical force to the shape memory polymer.
3. The method as defined in
4. The method as defined in
5. The method as defined in
6. The method as defined in
heating the shape memory polymer to a temperature above its switching temperature; and
cooling the shape memory polymer to a temperature below its switching temperature to substantially fix the shape memory polymer in the permanent shape.
8. The method as defined in
9. The method as defined in
10. The method as defined in
13. The method as defined in
14. The method as defined in
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18. The method as defined in
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The present disclosure relates generally to methods of using shape memory polymers.
Various automotive and/or aerospace parts including, for example, structural parts, internal cabin parts, and/or the like may be formed using conventional molding processes. One example of such a process includes reaction injection molding (RIM). In some instances, the RIM process may be used to form a part directly. Another example of a conventional molding process includes structural reaction injection molding (SRIM). In some instances, the SRIM process may be used in conjunction with a preform to form a reinforced part. Although suitable for forming parts having simple or even relatively complex shapes or geometries, forming more intricate parts (e.g., parts having one or more intricate features) using the RIM or the SRIM processes may, in some instances, be a challenge such as, for example, with maintaining dimensional targets and/or tolerances of the formed part.
A method, as disclosed herein, uses a shape memory polymer in a permanent shape, where the permanent shape is at least part of a predetermined part shape. The method includes converting the shape memory polymer from the permanent shape into a temporary shape, where the temporary shape is more open than the permanent shape. A material is sprayed onto at least one surface of the shape memory polymer in its temporary shape. The shape memory polymer, having the material on the at least one surface, is reverted back into its permanent shape.
Features and advantages of the present disclosure will become apparent by reference to the following detailed description and drawings, in which like reference numerals correspond to similar, though perhaps not identical, components. For the sake of brevity, reference numerals or features having a previously described function may or may not be described in connection with other drawings in which they appear.
Embodiment(s) of the method as disclosed herein may advantageously be used to i) form a preform for use in fabricating parts having one or more intricate features, ii) directly form a part having one or more intricate features, or iii) deposit a coating onto a part having one or more intricate features. As described further hereinbelow, shape memory polymers are utilized to open up the one or more intricate features, thereby enabling substantially uniform and more effective coating or establishing of materials on such features.
As used herein, an “intricate feature” refers to a portion of a part having a complex shape or geometry. Features having a “complex shape” or a “complex geometry”, as the terms are used herein, generally have a shape or geometry that renders the portion/feature difficult to form or coat using conventional processes. Such shapes or geometries include, for example, crevices, dips, or curves, and in some instances, such shapes have non-consistent cross-sections. In some instances, the intricate features have relatively small dimensions which are difficult to uniformly spray with any sort of material, such as, for example, paint, part-forming materials, materials such as fibers and/or binders to make preforms, etc.
Also as used herein, the phrases “to substantially uniformly spray,” “to uniformly spray,” or any other suitable variation refers to spraying (or otherwise establishing) a material onto a surface of the shape memory polymer in a controlled manner. In some instances, spraying is controlled to achieve uniformity in at least one of thickness, area, or density. In other instances, spraying is controlled so that the resulting layer may not be substantially uniform in at least one of thickness, area or density (i.e., the thickness, area and/or density along the layer varies).
Referring now to the drawings,
Referring now to
Since the methods disclosed herein may also be used to form a final part or a layer of a final part, the shape memory polymer 12 may be a mold for preforming or molding the final part, or a portion of the final part, as opposed to the preform screen 20 discussed herein. It is to be understood that the shape memory polymer 12 will be configured accordingly to have the desired part shape or to enable formation of the desired part shape.
The phrase “more open”, when used to describe the temporary shape of the shape memory polymer 12, 12″, refers to an expanded version of the permanent shape of the shape memory polymer 12, 12′. For example, if the permanent shape 12′ is a V-shape having a predetermined angle formed between two legs of the “V”, the “more open” temporary shape 12″ has a similar V-shape with a larger angle formed between the two legs of the “V” than the predetermined angle of the “V” for the permanent shape 12′. In some instances, the temporary shape 12″ is wider in lateral cross-section (along an axis A shown in the Figures) than the permanent shape 12′. It is to be further understood that, in some instances, the “more open” temporary shape 12″ also refers to a shape that is shallower in transverse cross-section (relative to an axis transverse to axis A, which would be coming into and out of the page in
It is to be understood that if the shape memory polymer 12 is integrated with a non-shape memory polymer material (shown as reference numeral 16 in
The shape memory polymer 12 includes at least one intricate feature 13. In the example shown in
It is to be understood that the shapes 12′, 12″ of the shape memory polymer 12 depicted in
Referring now to
As used herein, the term “switching temperature” of the shape memory polymer 12 refers to the temperature that causes the shape memory polymer 12 to deform, and to thus be capable of changing from its permanent shape 12′ into its temporary shape 12″, and visa versa. It is to be understood that the switching temperature varies depending on the type of shape memory polymer 12 selected. Non-limiting examples of suitable shape memory polymers include epoxy-based systems, acrylate-based systems, styrene-based systems, olefin-based systems, or combinations thereof. When the coating that is being applied requires subsequent curing, it is to be understood that the shape memory polymer 12 has a switching temperature greater than a curing temperature of a material 14 being coated on the polymer 12 (as will be described in further detail below). In some instances, such shape memory polymer material systems have switching temperatures ranging from about 100° C. to about 200° C. It is to be understood that any of the shape memory polymers 12 disclosed herein may be reinforced with inorganic fillers/fibers or other active materials. Non-limiting examples of suitable shape memory polymer fillers/fibers include electrically or magnetically and thermally conductive fillers/fibers, such as ferrite, magnetite, carbon fibers, carbon nanotubes, conductive polymers, and/or the like, and/or combinations thereof.
After the shape memory polymer 12 has been converted into its temporary shape 12″, the shape memory polymer 12 is cooled to a temperature below its switching temperature to temporarily fix the shape memory polymer 12 into its temporary shape 12″. As shown in
As referred to above, when the shape memory polymer 12 is in its temporary shape 12″, the shape memory polymer 12, 12″ has the more open shape. The more open shape generally exposes the intricate feature(s) 13 so that the material 14 is relatively easily sprayed on the surface 18 of the shape memory polymer 12. Depending, at least in part, upon the material 14 used and the purpose for coating, the material 14 may be subjected to curing (which will be described further hereinbelow). It is to be understood that, in some instances, the sprayed layer of the material 14 is substantially uniform in thickness and in surface area, and that the opened configuration of the features 13 enables such controlled coating. It is to be further understood that the application of the material 14 may be controlled to form a layer of the material 14 that has a desirable non-uniform thickness.
In an embodiment, the shape memory polymer 12 may be perforated. In this embodiment, prior to or during spraying of the material 14 onto the surface 18, a vacuum may be drawn from behind the surface 18. It is to be understood that the use of the vacuum assists in maintaining, for example, fibers or other materials 14 on the surface 18.
Referring now to
After the preform 10, 10′ has been formed (i.e., after the material 14 is cured), the preform 10, 10′ may be removed from the preform screen 20 (i.e., the shape memory polymer 12). In a non-limiting example, removal of the preform 10, 10′ may be accomplished by heating the shape memory polymer 12 above its switching temperature to render the preform screen 20/shape memory polymer 12 deformable, and then separating the deformed shape memory polymer 12 from the preform 10, 10′. It is to be understood, that such removal may be accomplished for any shapes of the shape memory polymer 12. It is further to be understood that if the shape of the shape memory polymer 12 does not include any intricate features (i.e., those that would normally render the shape memory polymer 12 die-locked in (i.e., non-removable from) the preform screen 20), removal of the preform 10, 10′ may, in some instances, be accomplished without the heating and the deforming steps.
To reiterate from above, the preform 10, 10′, having the predetermined part shape, may be used in a subsequent process for forming the part. In a non-limiting example, the part may be formed using a conventional molding process, examples of which include compression molding, injection molding, extrusion molding, and/or the like. Furthermore, the shape memory polymer 12 (in these examples used as a preform screen 20) may be reused to form another preform 10, 10′ having the desired part shape. If a thermoplastic material is used for the shape memory polymer 12, and if, for example, another part shape is desired, the shape memory polymer 12 may be reshaped and set into a new permanent shape. This may be accomplished, for example, using a suitably shaped mold and a heating and cooling sequence, where heating is accomplished above the highest melting transition temperature of the thermoplastic material. The examples of the method described above may then be used to form another preform using the reshaped shape memory polymer preform screen 12, 20 formed from the thermoplastic material. It is to be understood that the shape memory polymer 12 formed of a thermoplastic material may similarly be reshaped when it is used as a mold for forming the final part.
It is to be understood that if a thermoset material is used for the shape memory polymer 12, then a new permanent shape cannot be programmed. In other words, although the shape memory polymer 12 formed from a thermoset material may be used a number of times to produce the same, unique part, it is to be understood that such shape memory polymer 12 formed from a thermoset material cannot be reprogrammed in a different permanent shape.
Furthermore, when the shape memory polymer 12 is used as a layer for forming a final part, it becomes a portion of the final part, and thus will not be reshaped.
Another example of the coating method is shown in
Referring now to
As shown in
While not shown in the
As previously mentioned, it is to be understood that examples of the method disclosed hereinabove may also be used to form a final part instead of a preform 10, 10′. For example, using the example of the method shown in
Also as previously mentioned, it is to be understood that the shape memory polymer 12 may be a final part, and the methods disclosed herein may be used to paint or apply another desirable coating to the final part.
It is also to be understood that examples of the method disclosed hereinabove may be used to form or coat various automotive and/or aerospace structural parts, internal cabin parts, and/or the like. However, the examples of the method may also be used to form or coat other parts that are used in applications outside of the automotive and/or aerospace industries. Non-limiting examples of the other parts include mirrors, glass structures, various electronic components, bathroom fixtures, drinking cups with ornamental designs, storage containers with multiple separators, and/or the like, and/or combination thereof.
While several embodiments have been described in detail, it will be apparent to those skilled in the art that the disclosed embodiments may be modified. Therefore, the foregoing description is to be considered exemplary rather than limiting.
Rousseau, Ingrid A., Kia, Hamid G., Owens, John N., Berger, Elisabeth J.
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